1. Field of the Invention
The invention is directed to an electric drive with brakes, in particular for hoists, lifting devices or positioning transporting systems. The brakes have a brake disk which is movable axially on a motor shaft so as to rotate therewith via a toothing and which has brake faces at both sides. The brake disk can be pressed against stationary opposing or counter-brake disks by a spring force. An electromagnetic device is also provided which, when connected to current, causes the brake to be released against the spring force.
2. Description of the Prior Art
Direct current brakes are most commonly used for such drives, however, they have time constants that can be improved only at additional cost (e.g. DE 13 03 888).
In hoists, lifting devices and positioning transport systems, it is advantageous to use drives with fast braking.
Furthermore, in known a.c. brake systems the pole faces are rigidly attached and machined so as to have a small magnet gap when leaving the factory. Due to additional mechanical machining work, these systems are expensive and extremely sensitive to wear-induced changes in the magnet gap, which adversely affects operation. Additionally, an irritating hum normally develops after a certain period of time.